Cryptology ePrint Archive: Report 2010/143

Small Scale Variants Of The Block Cipher PRESENT

Gregor Leander

Abstract: In this note we deŻne small scale variants of the block cipher present [1]. The
main reason for this is that the running time of some recent attacks (e.g. [2, 3])
remain unclear as they are based on heuristics that are hard or even impossible
to verify in practice. Those attacks usually require the full code bock of present
to be available and they work only if some independence assumptions hold in
practice. While those assumptions are clearly wrong from a theoretical point of
view, the impact on the running times of the attacks in question is not clear.
With versions of present with smaller block size it might be possible to verify
how those attacks scale for those versions and hopefully learn something about
present itself.